Composite polyamide filaments with improved potential crimpability and method of making the same



United States Patent 3,397,107 COMPOSITE POLYAMIDE FILAMENTS WITH IM- PROVED PGTENTIAL CRIMPABILITY AND METHOD OF MAKING THE SAME Isao Kimura, Osaka-ski, Japan, assignor to Kanegafuchi Boseki Kabushiki Kaisha, Tokyo, Japan No Drawing. Filed July 22, 1965, Ser. No. 474,182 14 Claims. (Cl. 161173) The present invention relates to composite polyarnide filaments with an improved potential crimpability consisting of two continuous adherent eccentrically arranged components of synthetic linear polyamides, in which one component consists essentially of a homopolyamide and the other component consists essentially of a copolyamide of bifunctional polyarnide-forming constituent containing in its main molecular chain the atoms of the Group VI of the periodic system having an atomic number not more than 16 and at least one of e-caprolactam and hexamethylenediammonium-adipate.

The recent known process of providing self-crimpable synthetic fibers consists of simultaneously spinning two or more components from the spinneret in side-by-side relationship or in an eccentrically disposed sheath-core arrangement. However, if in such a case the individual polymeric components are of essentially different characteristics they have low adhesion with each other.

When they are spun into composite fibers, they are easily separated from each other with a slight force. Consequently, the object of obtaining the desired fibers is usually attained by using polymers of the same kind, but of different chemical composition (for example, the pair of components such as polyamide-polyamide, polyesterpolyester and polyacrylonitrile-polyacrylonitrile combination).

An important factor in evaluating the quality of the final product is the crimp retentivity under stress of the crimped fiber thus obtained. If such fiber is inferior to the fiber originally made of a single polymer in respect of tensile strength, softening point, light-stability, dyeability and chemical resistance, then it will, of course, be undesirable. In the case of nylon 6 (poly e-caprolactam) or nylon 66 (hexamethylene-adipamide) it is known that the melting point of the polymer presents in copolymerization concave curves against the copolyrnerization ratio.

Consequently the melting point of copolymers in practical use should fall within the range where it is not much different from that of nylon 6 or 66.

A first object of the present invention is to provide composite polyarnide filaments which have excellent physical properties.

A second object is to provide composite polyarnide filaments which have excellent potential crimpability.

A third object is to produce composite polyarnide filaments which are better than any known polyamide-base synthetic fibers as regards dyeability, hygroscopicity and electrical properties.

The inventor has discovered that it is possible to obtain composite polyarnide filaments which retain an extremely high crimpability and are not inferior to any fiber of a single polymer with regard to other fibrous properties and in fact are even improved in some respects by the use of the nylon copolymer's which are made from special nylon salts and e-caprolactams (hereinafter referred to as lactam) or nylon 66 salts in high or low copolymerization ratios. The aforementioned special nylon salts are bifunctional polyamide-forming constituents containing in their main molecular chain atoms which fall within the Group VI of the periodic system and have an atomic number not more than 16. Said salts are prepared from the diamines or dicarboxylic acids having ether bonds or thioether bonds in their main molecular chain.

The reason why crimped filaments can be obtained by uniting two types of polymer having different compositions in side-by-side or eccentric sheath and core relationship with respect to each other along the length of the length of the filaments is solely due to the different degrees of shrinking or swelling which said polymers undergo when heat or swelling agents are applied. The aforesaid difference in swelling and contraction can be produced most effectively by varying the intrinsic crystalline form of the individual polymers used. The copolymers containing in their main molecular chain ether bonds or thioether bonds assume different crystalline structures from nylon 6 or 66. Furthermore, the ether or thioether bond has diiferent degrees of freedom in relation to thermal motion as compared with the methylene radical. For this reason the polymer suffers greater internal strains and partly takes on an elastomeric nature in its molecular structure. Thus the composite filament consisting of two components of which one is the homopolymer and the other is the copolymer containing ether or thioether bonds develops more remarkable crimps through the application of heat or swelling agents under relaxed conditions after drawing than any of the known composite fibers. This effect is more prominent as compared with the fiber made of the polymer whose basic structure consists of the methylene group alone. Therefore one can easily understand what a great effect is produced by the chains containing ether or thioether bonds.

The diamines and dicarboxylic acids containing ether or thioether bonds which can be used in the manufacture of the composite polyarnide filaments claimed in the present invention are, for example, as follows:

bis('y-aminopropyl) ether, bis('y-aminopropoxy) methane, bis('y-aminopropoxy) ethane, bis(w-aminopentyl) ether, 1.4-bis('y-aminopropoxy) phenyl, bis[4-(' -aminopropoxy) phenyl methane, bis[4-(' -aminopropoxy) phenyl] propane, 1.4-bis ('y-aminopropoxy) cyclohexane, bis([3-aminoethoxy) ethane, bis('y-aminopropoxy) propylene, bis( -aminopropoxy) propane, bis('y-aminopropoxy) butane, ohm-bis[4-(y-aminopropyD-phenoxy] methane, oLw-biS [4- -aminopropyl) -phenoxy] ethane, ocw-bis [4-(y-aminopropyD-phenoxy] propane, emu-bis [4-( -aminopropyl)-phenoxy] butane, ecu-bis[4-( -aminopropyl) phenoxy] heptane, emu-bis [4-('y-aminopropyD-phenoxyl hexane,

w.w-diamine of pplyethylene glycol or polypropylene glycol having a molecular weight of 300 to 1500, and other substances indicated by the general formula of H N(CH ),,S(CH ),,NH (where 11:2 to 5). In addition to the above, any other substances that contain ether or thioether bonds in the main chain are usable for the production of the composite polyarnide filaments under consideration.

The dicarboxylic acids that can be employed correspondingly with the aforementioned diamines are oxalic acid, adipic acid, sebacic acid, terephthalic acid, iso- 3 phthalic acid, and the like. In addition, the following dicarboxylic acids containing ether or thioether bonds are also usable:

(fi-carboxyethyl) ether, bis(fl-carboxyethoxy) methane, bis(fl-carboxyethoxy) ethane, bis(w-carboxytetramethyl) ether, 1.4-bis( 3-carboxyethoxy) phenyl, bis[4-(fi-carboxyethoxy)-pbenyl]methane, bis [4- (fl-carb oxyethoxy) phenyl] propane, 1.4-bis(fi-carboxyethoxy) cyclohexane, bis (fl-carboxymethoxy) ethane, bis(fl-carboxyethoxy) propylene,

bis 8-carboxyethoxy) propane, bis(.fl-carboxyethoxy) butane, 1.2-bis( -carboxyphenoxy) ethane, 1.3-bis -carboxyphenoxy) propane, 1.4-bis( -carboxyphenoxy) butane, l.6-bis( -carboxyphenoxy) hexane, 2.2-bis [/3- -carboxyphenoxy) -ethyl] ether,

w.w'-dicarboxylates of polyethylene glycol or polypropylene glycol having a molecular weight of 300 to 1500 and other substances indicated by the general formula of HOOC (CH S(CH COOH (where 11:2 to Since other substances than those given above are usable if they contain ether or thioether bonds in the main chain, the foregoing list is not restrictive. In addition to the aforesaid diamines containing ether or thioether bonds, other diamines which can be used correspondingly with the abovementioned carboxylic acids may include linear aliphatic diamines such as ethylenediamine, hexamethylenediamine, nonamethylenediamine and undecamethylenediamine and other diamines having an aromatic nucleus such as -xylylenediamine and metaxylylenediamine.

Further, other substances which can be used in the present invention are w-amino acids containing ether or thioether bonds, for example, p-(v-aminopropyl) phenoxy acetate.

Following is a general process of manufacturing the crimped composite polyamide filaments of the present invention utilizing the aforementioned substances containing ether or thioether bonds.

The copolyamides are prepared from either a set of components consisting of diamines containing ether or thioether bonds and aliphatic or aromatic dicarboxylic acids or a set of diamines and dicarboxylic acids each containing ether or thioether bonds or a set of dicarboxylic acids containing ether or thioether bonds and aliphatic or aromatic diamines. The individual components of these sets are reacted in equal molar ratios in aqueous solutions to produce nylon salts. In this case said salts are separated or not, depending upon whether non-solvents or not are added. Then the salts are copolymerized with lactam or nylon 66 salt in given ratios, at predetermined temperatures and for predetermined lengths of time, keeping the reaction from the effect of oxygen. On the other hand lactam or nylon 66 salts are singly polymerized as homopolyamide under predetermined conditions. These two polymers are melted separately and extruded simultaneously through the same orifices to form unitary filaments. Upon solidification they are wound on a reel. The nylon filaments which have been drawn under the predetermined conditions are further subjected to wet or dry heating at predetermined temperatures and for predetermined lengths of time under relaxed conditions. Thus composite polyamide filaments are obtained which have extremely good physical properties and highly improved crimps.

The crimped composite filament produced by the process of the present invention has a far greater crimp-retentivity under tension than any other crimped nylon filaments obtained by the known processes. Furthermore, the filaments of the present invention overcome various shortcomings of the known synthetic fibers, because they have greater dyeability than common polyamidic synthetic fibers, are provided with greater hygroscopicity due to the content of oxygen or sulfur atoms, and are less subject to static changes on account of their improved hygroscopicity. In addition it has been confirmed that the tensile properties of crimpable composite polyamide filaments falling within the range of structure obtainable by the present invention are not different at all from those of conventional nylon filaments. It is also recognized that if the filaments of the present invention contain as one component a copolymer with an aromatic nucleus in its molecular chain they even produce an increase in the Youngs modulus. The final product, incorporated with this characteristic, has further improved its quality.

The present invention will be more clearly understood with reference to the examples which follow. However, it should be noted that the present invention is not limited to these examples.

Example 1 132 g. of bis('y-aminopropyl)ether and 166 g. of terephthalic acid were mixed and dissolved in a hot aqueous solution. The mass was introduced into isopropyl alcohol to crystallize nylon salts. Said salt was further purified and dried. A mixture of 10 g. of this salt, g. of lactam and V mol. of glacial acetic acid per mol. of the total mass was heated and polymerized in CO gas streams at 240 C. for 7 hrs. to produce copolymers. On the other hand 100 g. of lactam, 5 g. of e-aminocaproic acid and V mol. of glacial acetic acid per mol. of the total materials used were mixed, heated and polymerized in CO gas streams at 250 C. for 7 hrs. to produce nylon 6 polymer. The two polymers thus obtained were melted in a separate system at 240 C. They were simultaneously extruded together through 0.3 mm. orifices of a spinneret. The composite nylon filaments obtained by uniting said two components were wound on a reel.

The filaments produced were drawn to 4.4 times the original length and subjected to Wet heat treatment with no tension at C. for 10 min. Thus crimped nylon fila- Crimp retention under tension (x) Load (mg/d.) Longitudinal contraction percentage due to crimps (percent) 0 85.0 0.07 79.0 0.14 72.7 0.7 47.1 1.4 36.7

(x) The crimp retention under tension was calculated as follows:

Multi-filaments comprising 40 mono-filaments (30 cm. long) were treated with hot water at 95 C. for 10 min. under varying loads to develop crimps and dried at room temperature. The length of the crimped filaments after the above-described treatments against the original length was shown in percentage.

I Next, for comparison, hexamethylenediamine was used 1n place of bis('y-aminopropyl)ether. Exactly in the same way as practiced in the foregoing experiment, said diamine was reacted with terephthalic acid to form nylon salts. When the polymer obtained by copolymerization of said salts with lactam was used as one component of composite filaments, the crimp retention measured under tension, gave the following results:

Load (mg./d.): Longitudinal contraction percentage due to crimps (percent) Also crimped filaments prepared in this experiment were dyed with Japanol Brilliant Blue 6BKX (manufactured by Sumitomo Chemical Co., Ltd.) under the conditions of 2% dye concentration, 100-fold bath ratio, 70 C. and /2 hr. When the cross-section of these filaments were inspected it was recognized that the copolymer component alone was distinctly colored blue.

Example 2 Nylon salts were prepared from 176 g. of biS('y-arninopropoxy) ethane and 166 g. of terephthalic acid in the same way as in Example 1. g. of said salt, 90 g. of lactam and mol. of glacial acetic acid per mol. of the total materials used were mixed, heated and polymerized in CO gas streams at 240 C. for 7 hrs. to produce copolymers. As in Example 1, spinning was carried out by uniting said copolymer with nylon 6. After drawing, the filaments were subjected to wet heat treatment at 95 C. to develop crimps. The filaments thus obtained extremely remarkable crimps, and also an excellent touch. The properties of these filaments were as follows:

Fineness d 14.9 Tensile strength g./d 4.6 Elongation-at-break percent 26.4

Crimp retention under stress Load (-rng./d.): Longitudinal contraction percentage due to crimps (percent) When the filaments were dyed with Japanol Brilliant Blue 6BKX the copolymer component alone presented distinct colors as in Example 1.

'Example 3 Pure nylon salts were prepared from 230 g. of 1.4-bis- -a-minoporpoxy)cyclohexane and 146 g. of adipic acid in the same manner as in Example 1. 7 g. of said salt and 93 g. of lactam were mixed, heated and polymerized in CO gas streams at 240 C. for 7 hrs. to produce copolymers. Crimped filaments were prepared by uniting said copolymers with nylon 6 as in Example 1. The crimped retention of these filaments under stress was as follows:

Load (mg./d.): Longitudinal contraction percentage due to crimps (percent) Example 4 Example 1. The crimp retention of these filaments under stress gave the following values:

Load (mg/d): Longitudinal contraction percentage due to crimps (percent) Example 5 Nylon salts were prepared from 162 g. of his (fit-carboxyethyl) ether and 136 g. of paraxylylenediamine in the same manner as in Example 1. 15 :g. of said salt, g. of lactam and mol. of glacial acetic acid per mol. of the total materials used were mixed, heated and polymerized in CO gas streams at 240 C. for 7 hrs. to produce copolymers. Composite nylon filaments were melt-spun unit ing said copolymer with nylon 6 and crimps were developed in the same manner as in Example 1. The crimp retention of these filaments under stress was highly excellent. When the filaments were dyed with Japanol Brilliant Blue 6BKX as in Example 1, the copolymer component alone was easily colored.

When the electric resistance of the filaments thus obtained was measured, the resistance per cm. of the filament was 7X10. In contrast, the electric resistance of nylon 6 was measured to be 8X10. This shows that the nylon filaments by the present invention had an anti-static property.

Example 6 80 g. of the nylon salts which were prepared from his (v-aminopropynether and terephthalic acid and 20 g. of lactam were mixed and polymerized in CO gas streams at 240 C. for 7 hrs. Melt-spinning was carried out uniting said copolymer with nylon 6. After drawing, dry heat treatment was conducted to develop crimps. The filaments thus obtained had the following properties:

Fineness d 16.7 Tensile strength g./-d 4.1 Elongation-at-break percent 18.7 Youngs modulus g./d 29.1 Yield stress g./d 0.57

Crimp retention under stress Load (mg./d.): Longitudinal contraction percentage due to crimps (percent) Example 7 .Nylon salts were prepared from 148 g. of his (y-aminopropyl) sulfides and 166 g. of terephthalic acid in the same manner as in Example 1. 10 g. of said salt, g. of lactam and glacial acetic acid corresponding to A mol. per mol. of the total materials used were mixed, heated and polymerized in CO gas streams at 240 C. for 7 hrs. to produce copolymers. Spinning was carried out uniting said copolymer with nylon 6, as in Example 1.

After drawing, wet heat treatment was performed at C. to develop crimps. The crimp retention of these filaments under stress was as follows:

Load (mg./d.): Longitudinal contraction percentage due to crimps (percent) Example 8 p Nylon salts were prepared from 132 g. of his -aminopropyl) ether and 302 g. of 1.2-bis -car-boxyphenoxy) ethane in the same manner as in Example 1. 10 g. of said salt, 90 g. of lacta'm and 4 mol. of :glacial acetic acid per mol. of the total materials used were mixed, heated and polymerized in CO gas streams at 240 C. for 7 hrs. to produce copolymers. Spinning was carried out uniting said copolymerwith nylon 6 to produce composite filament and crimps were developed as in Example 1. The crimp retention under stress of the filaments obtained was as follows:

Load (mg/d): Longitudinal contraction percentage due to crimps (percent) Example 9 As in Example 1, 10 parts by weight of terephthalate of his ('y-aminopropyl) ether and 90 parts by weight of e-caprolactam were copolymerized to produce copolyamide. Composite nylon filaments were melt-spun at 270 C. uniting said copolyamide with polyhexamethyleneadipamide (nylon 66) having a specific viscosity of 0.93 in m-cresol solution at 30 C. and the filaments were wound on a bobbin. After being drawn 4.4 times their original length at 70 C., filaments with the following properties were obtained:

Fineness d 15.2 Tensile strength g./d 5.6 Elongation-at-break percent 31.8

Load (mg./d.): age due to crimps (percent) What is claimed is:

1. A composite polyamide filament with an improved potential crimpability consisting of two continuous adherent eccentrically arranged components of synthetic linear polyamides, in which one component consists essentially of a homopolyamide and the other component consists essentially of a copolyamide of a bifunctional polyamide-forming constituent containing in its main molecular chain atoms from Group VI of the periodic system having an atomic number not more than 16 and at least one substance selected from the group consisting of e-caprolactam and hexamethylenediammonium-adipate.

2. A composite polyamide filament according to claim 1, wherein the homopolyamide is selected from the group consisting of poly-e-caproamide and polyhexamethyleneadipamide.

stance selected from the-group.consistingaof e-caprolac;

tam and hexamethylenediammonium adipate..

5. A composite polyamide filament according toaclairn 1, in which the bifunctional polyamide-forming cnnstitu ent is selected from the group consistingof diamine, .di.- carboxylic acid and w-amino-carboxylicacid.e

6. A composite polyamide filament according to claim 5, wherein said polyamide-forming constituentdcontain a bond selected from ether and thioether bonds:

7. A composite polyamide filament .accordingto .nclairn' 1, wherein the copolyamide contains-in its main molecular chain a bond selected from ether=and thioet-her .b0nds=..

8. A method of forming a composite polyamide fiber having high crimpability, said method comprising spinning two filaments into a composite fiber, said filaments having different intrinsic crystalline forms to provide different degrees of dimensional modification of the filarnents upon the application of heat and swelling agents, said filaments each being a synthetic linear polyamide, one being a homopolyamide of a nylon salt containing a.v methylene radical, the other being a copolyamide of a bifunctional polyamide-forming constituent containing atoms from Group VI of the periodic table having an atomic number less than 16 in its main molecular chain and at least one substance selected from the group consisting of e-caprolactam and hexamethylenediammonium-adipate.

9. A method according to claim 8 in which the nylon salt is one of poly-e-caproamide and poly-hexamethyleneadipamide.

10. A method according to claim 8'in which the bifunctional constituent of the copolyamide contains oxygen atoms.

11. A method according to claim 8 in which the bifunctional constituent of the copolyamide contains sulfur atoms.

12. A method according to claim 8 in which the bifunctional polyamide-forming constituent is selected from the group consisting of diamine, dicarboxylic acid and w amino-canboxylic acid.

13. A method according to claim 12, wherein said polyamide-forming constituent contains a bond selected fro ether and thioether bonds. 1 I

14. A method according to claim 8, wherein the copolyamide contains in its main molecular chain a bond selected from ether and thioether bonds.

References Cited UNITED STATES PATENTS 2,987,797 6/1961 Breen 161 '17s' 

1. A COMPOSITE POLYAMIDE FILAMENT WITH AN IMPROVED POTENTIAL CRIMPABILITY CONSISTING OF TWO CONTINUOUS ADHERENT ECCENTRICALLY ARRANGED COMPONENTS OF SYNTHETIC LINEAR POLYAMIDES, IN WHICH ONE COMPONENT CONSISTS ESSENTIALLY OF A HOMOPOLYAMIDE AND THE OTHER COMPONENT CONSISTS ESSENTIALLY OF A COPOLYAMIDE OF A BIFUNCTIONAL POLYAMIDE-FORMING CONSTITUENT CONTAINING IN ITS MAIN MOLECULAR CHAIN ATOMS FROM GROUP VI OF THE PERIODIC SYSTEM HAVING AN ATOMIC NUMBER NOT MORE THAN 16 AND AT LEAST ONE SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF E-CAPROLACTAM AND HEXAMETHYLENEDIAMMONIUM-ADIPATE. 